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Does anybody have experience using an isolation transformer with their front-end digital components?
I am experiencing noise from my digital components into my system. It presents as high frequency interference thru the speakers once the components are warmed up.
This interference is being sent back to the mains and can be heard when music is being played or idle.
I'm using an ARC CD3 mk II CDP, Chord DAC, and a NAD CD player. I have a 20 amp dedicated line with Blue Circle power conditioning at the wall. A Furman power strip for the low-current components is plugged into the PC and my amp plugs into the wall duplex outlet. Interconnects are all single-ended.
The ARC sends this noise thru the system when used as a stand-alone CDP, and also when used with the DAC as a transport. Same with the NAD.
Somebody on another forum was using a Tripp-Lite IS250HG Isolation Transformer...
https://www.amazon.com/dp/B0000ET7Q6/ref=wl_it_dp_o_pC_nS_img?_encoding=UTF8&colid=29XG41GAZ363K&coliid=IK7439TOTDZ8K
So, I'm wondering if using an isolation transformer will stop the digital interference from bleeding back into the mains. Any help is appreciated.
Follow Ups:
Keep removing the various Barnacle bits attached to your NAD CDP until it becomes obvious which Piece is is the problem (junk)
I removed the NAD a couple weeks ago; was using it as a transport. Right now, the noise can only be heard when the ARC CDP is being used. It has always been coming from the ARC.
But, the Tripp-Lite Isobar has reduced the amount of time that the noise is present.
Unplug the ARC ?
First try it sans the Power Magic filter/conditioner gizmos.
Not convinced those things give benefit. possibly they are interacting?
Dunno though as I've never used such and My setup dead silent..NO noise whatsover. Same as when unplugged.
And I did Zero to get it there.. besides decent gear.
Have experimented for many months...
All power conditioning was removed, tried different power cords, cheater-plugs, the only components plugged into dedicated line were amp, preamp, and ARC CD, unplugged the ARC and noise was gone. (The ARC is SS, not tube).
The noise was eliminated when I had full system hooked up and ARC was plugged into a different receptacle and circuit.
I'll see what happens when the isolation xfmr arrives.
**But a new development yesterday; turned on the tube preamp and the noise/interference was present. Preamp was turned off overnite, so noise from CDP was present on cold start. DAC was unplugged.
Thanks to everybody for their interest.
Lowrider, did you have success in identifying the source of the noise?
_
Ken Newton
Knewton,
I've been having some success lately using the Tripp-Lite isolated power strip. I've had some listening sessions uninterrupted by noise/interference.
When the noise does present after the system has been running, I've turned off the preamp and let it cool down for a few hours. Then upon powering up later, the noise was still there. (I know it's possible that caps may still be charged).
The only digital devices being used are the ARC CDP and the Chord DAC. I believe the ARC is causing interference based on the different level of noise produced by using different power cords and the elimination of noise when CDP was moved to a different circuit.
So, for $125 I ordered a Tripp-Lite Hospital iso transformer from Ebay. They sell for $260 new, so this is worth a try to use on the digital source.
So, you did not try replacing the Atma-Sphere preamp with your other line stage?
_
Ken Newton
Edits: 07/04/16 07/04/16
Ken, unfortunately I've been sick and in the hospital for tests, so I haven't had the energy to swap out any components.
I can now say for certain that the only digital component in use (plugged in) when the noise presents is the ARC CD.
Sorry, to hear that you've been ill. Get well soon.
_
Ken Newton
Thanks for the kind words, Ken.
Some DACs have an isolation transformer built in to the digital coaxial input so the groynd doesnt transfer noise. How is you CDP connected to the DAC? Some try optical as there is no ground that. I'm all for isolation transformers so its worth a shot especially if you can borrow or get one on loan.
ET
Does anyone make isolation transformers that I can use with each of my six decitated lines? I'm looking for separate ones not one in a big box.
FWIW I like to use small "isolation" units, a separate one for each major component when possible. Especially to keep the digital sources away from the analog ones, and to keep stuff with motors away from...everything else (that's mostly in my head, probably).
This isn't as bad as it sounds, since each unit can possibly power multiple units when only one is used at a time. e.g. I find no prob putting a DAC and pre on the same unit, both used together, or conversely putting a TT, tuner, CDP, BDP and file server "terminal" on the same unit because they won't ever be used at the same time.
Yes, large units can hum, but it isn't legal in most (all?) of the U.S./Canada to put *certain* types of conditioners in a remote location, they need to be "local". Another advantage for smaller units that tend to hum much less. Multiple smaller units typically costs more though.
knewton, here goes...
1. I have only noticed the noise after system has been warmed up and running. Actually, digital does not have to playing, only selected on the preamp while the system sits idle. But at full operating temp.
2. The noise does stop when I disconnect the analog RCA interface between the preamp and the digital units.
4. I have removed the power conditioner and noise was still present. I have one 20a line with a duplex receptacle, so I needed the Furman in one outlet. Amp is direct into 2nd outlet.
Since the Chord DAC uses a switching PSU wall-wart and is noisy, it was removed. All tests were done with pre and ARC CDP plugged into Furman.
Additional:
- different power cords were used on the pre and the CD. Stock PC on CDP gave the most suppression to the noise.
- currently using "cheater-plugs" on CDP and preamp.
- Noise/interference was eliminated when I plugged CDP into a separate line dedicated for the washer/dryer. This is the only other dedicated line to the circuit box.
Thanks so far.
Okay, thanks.
That the noise shows up after the system is warm argues against it simply being due to some power main related ground loop, which should manifest either hot or cold. However, it may be that some electrical component is malfunctioning in a manner to permit a ground loop after becoming warm. The fact that it manifests with both CD players, or with the DAC, argues against those units malfunctioning. So, some more questions:
1. Please describe the noise? Is it low in frequency, or is it more mid-band? Is it raspy or distorted sounding, or is it more of a hum? Is it steady, or does it have more of an intermittent character?
2. Are you utilizing the same pair of analog interconnect cables between the digital source units and the preamp? I mean, do the Chord DAC, ARC player and NAD player each have their own dedicated pair of interconnect cables? Related to that question, are you using the same preamp inputs for connecting the digital source units? If you answered yes to either question, try using using a different pair of interconnects and a different preamp input.
_
Ken Newton
Appreciate your interest, Ken.
1. The noise is always the same and always steady. It is a very high-frequency, narrow band sort of "whine" or low volume "screeching" raspy type noise. When I am troubleshooting, the volume pot is turned down, a digital device is selected, and the noise is audible. Turning on MUTE will defeat the noise. (Atma-Sphere SE preamp, which replaced a Rogue).
(I have tinnitus which comes and goes, so for a while I thought the noise was my medical issue. I have been tested and have excellent hearing for a mid-50 year old; some low frequency loss, but I can still hear 19K just like when I was a teenager).
I'm guessing that the noise is in the 5-10kHz range.
2. My components have dedicated pairs of interconnect cables, mostly Purist Audio. For the sake of testing, right now Belden IC's are connected, and I have tried each input.
The reason I am asking about the use of an isolation transformer for the digital components is because I recently tried using a Tripp-Lite Isobar for the ARC and the DAC. It's selling point is that it has isolated filter banks for receptacles and toroidal chokes.
Anyway, there were times when the digital noise was eliminated, but overall the unit was not effective. Sometimes it would suppress the noise, then the filtering would fail...about a 25% success rate.
Just wanted to say that I'm no EE, but I know that some digital circuits can feed noise from the device back down the power cord into the AC line that is shared by analogue components.
What I don't know is if the gain of my CDP and amp plays a part in the level of this return signal. The ARC CDP and my amp both have very high gain.
Okay, this is as I had suspected. A high pitched noise is likely not due to a mains ground loop. You may be experiencing either RF intrusion, or some gain stage oscillation (oscillation is more my suspicion, since the noise only appears after warm up). So, we appear to have reduced the possibility of the digital source components, the interconnects or the power amp being the problem. I say the power amp too, because the noise stops once you mute the preamp output feeding the amp. Signs appear to be pointing to the preamp.Next, I suggest bypassing (completely removing) your Atma-Sphere preamp from your system chain. If you don't have a second preamp unit laying around in your basement then beg, borrow or steal one from a friend. Any cheap unit will do, the quality doesn't matter for your noise isolation test purposes. If you cannot access another preamp from somewhere, then perhaps your Chord DAC features a built in volume control, enabling it to be directly connected to your power amp.
If the preamp turns out to be the source of the noise, it may have a bad tube or a tube with pins poorly contacting it's socket. If it's not due to something easy to fix yourself, like that, then the preamp will probably need professional servicing. If the problem turns out NOT to be the preamp then, unfortunately, it would be hard to determine where else to point you via remote troubleshooting. So, keep your fingers crossed. :)
_
Ken Newton
Edits: 06/25/16 06/25/16 06/25/16 06/25/16 06/25/16 06/25/16
Ken, I appreciate your time and you may be right about having a preamp issue. I bought the pre new in January and it has been modded. Gain has been lowered to match the high gain of my SS amp and a 6dB pad added for the gain of the ARC CD. Higher quality pots replaced the stock. I have to believe that Ralph would not let a unit leave his shop with any tech problems. He even setup the preamp and tested it using a SS amp.
I have rolled the tubes, but I can check again, and I do own a small line stage.
I'm certainly not dismissing your diagnosis, since it was done very thoughtfully and methodically.
The fact that when I ran the digital from the separate AC line for a few days and the offending noise was eliminated still makes me wonder if isolation would work. Also, the use of the Tripp-Lite power strip did provide some periods of noise-free use of my system.
This may not be relevant but I just eliminated a 7.5 kHz intermittent pulse of about 10 db by changing the balanced XLR cables to a model that may be better shielded. I had this same problem with different sets of equipment and i think in both instances it was due to poorly shielded interconnects. The ones i needed to replace were not cheap and are generally well reviewed. The interconnects were between a tube preamp and SS amp.
motberg,
That's an interesting thought regarding my issue. I've substituted many ICs from the various digital, but never tried swapping out the preamp to amp IC. (It's unbalanced).
Lowrider, you're welcome.The fact that the noise went away when using different power outlets may not be as significant as the fact that it later returned. Which may mean that the temporary absence of the noise was simply coincidental, possibly being more correlated with the simple fact that the components had to be powered off in order to switch them over to other outlets, however, it's really difficult to say anything conclusive yet.
Definitely insert that back up line stage in place of the Atma-Sphere unit to see whether the noise is affected. Good luck.
_
Ken Newton
Edits: 06/26/16 06/26/16 06/26/16 06/26/16 06/26/16
For my main components I use a Furman REF20i
For the digital I use a PS Audio P600.
I have a separate excellent power conditioner lying around doing nothing. That sounds like a good idea. I will give it a try. Thanks!
Dave
A few questions:
1. The noise only begins AFTER your components have warmed up, but is not present while they're cold, is that correct?
2. Does the noise stop when you disconnect the the analog RCA interface between the preamp and the digital units?
3. If the answer to question 2 is no, then does it stop when you disconnect the interface between preamp and power amp?
4. How have you determined that the noise is being sent back through the mains connection? Does the noise stop if you bypass the Blue Circle and Furman power conditioner units?
_
Ken Newton
And keeping the RFI confined to the digital rig.
I use the Topaz Line 2 02406-01P3 1kVA ferro-resonant conditioner. Been using them for over 5 years.... They show up quite often on eBay. Relatively inexpensive compared to the high-end line conditioners out there now.
I heartily agree with this statement .Of all the "components" in my system , I think I may value my Equitech 1.5Q BPT as much as any other part of my system ( Maybe even a bit more ). I had been running my system through a PSA PP500 & was pretty satisfied with that configuration, but I was'nt quite prepared for the noisefloor drop that I experienced when I switched over to the Equitech .
For the better part of 2 days music listening I kept noticing that the played notes all seemed to have greater relief from where they seemed to be originating from ,on recording after recording. The music went from coming from a quiet place to coming from a quiet place with micro dimensionality attached to the music (that you weren't aware was even available from the recordings; & I'm not talking about music coming off of Vinyl here)
I ended up "repurposing" my PP500 to my Video system (Sony XBR,DVDO Edge, Oppo 95 BDP ,TIVO) where it's keeping me from thinking about upgrading,
Edits: 06/27/16
Inmate knewton is on the right track by asking him for more information rather than jumping to any premature conclusions.No properly functioning audio system should create digital noise in his speakers unless something is grossly wrong, whether he runs a power conditioner, power strip, or isolation transformer.... or not.
Such devices might seem to 'cure' his problem, but this problem should not exist at all in the first place.
My 2-cents worth.
Edits: 06/24/16 06/24/16
"No properly functioning audio system should create digital noise in his speakers unless something is grossly wrong, whether he runs a power conditioner, power strip, or isolation transformer.... or not."
What constitutes "properly functioning"?
Unless the product itself is designed with built-in mains isolation, I don't know of a digital audio source that doesn't add hash to the mains line. Whether it's "properly functioning" or not.
We can have faith that our digital sources don't put noise back on the mains line. But in my opinion, this tweak option doesn't hurt anything. (Except for a small ding to the pocketbook.) So this really isn't an issue at all.
Some folks may misunderstand the nature of various types of noise and associated power line filtering goals, in that digital noise, RFI, and EMI do not always tend to be audible in a gross manner, such as something one can identify or obviously point-out like audible high frequency hash or hiss, radio station broadcasts, and audible hum.
What is most beneficial about power line conditioners is addressing more subtle noise issues that are not so easy to identify, which pollute electronic parts/circuits in a manner that degrades the performance of those electronic parts/circuits performance rather than eliminating grossly audible noise artifacts. This is to say, even if you cannot hear any identifiable sounds that appear to be noise, the primary function of a power line conditioner is to allow electronic parts/circuits to function without a level of detrimental operational effects caused by more subtle noise issues that raise the noise floor.
As for isolation transformers, one might find a lowered noise floor at the expense of a degraded sonic signature caused by the isolation transformer itself, which is why isolation transformers intended for non-audio applications are not so popular with audiophiles. Like many things pertaining to audio gear, sonic trade-offs are often inevitable.
Thanks Todd. Is this small Topaz good enough to use for a DAC and transport?
http://www.ebay.com/itm/191842008876?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Beware of transformer noise. I had 2 and 5kVAs and both of them were noisy, at least in a50 Hz area. I had to banish one outside of my listening room.
Try to look for genuine ultra isolation units designed for the purpose. They are not cheap. Best if they give isolation figures over as wide a bandwidth as possible.
Perhaps you should ask ARC first as to why.
I hear a faint "hum" about 2 feet from the unit. That's not as bad as some other line conditioners I use, which can be heard a good 10 feet away. I run two units, one for the CD source on each system.The 1 kVA version should be plenty for a transport and DAC. (This unit should be robust enough for smaller power amplifiers or entire low-power systems.) It's the biggest isolation unit you can run safely off a standard 120V 15A outlet. (Topaz makes larger units, but require industrial mains that can handle more than 20A.)
Edits: 06/24/16
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